Vaginal infection and preterm labour

Maternal periodontal disease and preterm low birthweight: case-control study

Periodontal disease has been suggested to be an important risk factor for preterm low birthweight (PLBW). Here we report a case-control study of 236 cases (infants < 37 wks and weighing < 2499 g) and a daily random sample of 507 controls (> or = 38 wks and weighing > or = 2500 g). Clinical periodontal indices were measured on the labor wards. Associated risk factors for periodontal disease and PLBW were ascertained by means of a structured questionnaire and maternity notes. The risk for PLBW decreased with increasing pocket depth (odds ratio [OR] 0.83, 95% confidence interval [CI] 0.68 to 1.00). After adjustment for maternal age, ethnicity, maternal education, smoking, alcohol consumption, infections, and hypertension during pregnancy, this decreased further (OR 0.78, 95% CI 0.64 to 0.99). We found no evidence for an association between PLBW and periodontal disease. Our results do not support a specific drive to improve periodontal health of pregnant women as a means of improving pregnancy outcomes.

Risk score for antenatal bacterial vaginosis: BV PIN points

OBJECTIVE

Develop a clinical risk score to screen for antenatal bacterial vaginosis (BV), irrespective of symptoms.

STUDY DESIGN

Cohort study of 913 pregnant women with last menstrual periods between January 30, 1995 and February 22, 1997. BV was evaluated by Nugent-scored vaginal smears (scores of 7 to 10 considered positive) between 24 and 29 weeks' gestation. Forty-four potential risk factors were assessed.

RESULTS

17.8% of women had BV, of whom 22% were screened for BV by the usual care provider. Logistic regression-adjusted analyses found six predictors: vaginal pH>4.5 (OR=11.6, 95% confidence interval [CI] [7.8, 17.2]); black race (OR=1.9, 95% CI [1.3, 2.8]); condom use during pregnancy (OR=1.6, 95% CI [1.0, 2.5]); antenatal BV (OR=1.7, 95% CI [1.0, 2.8]); absence of sperm on smear (OR=1.7, 95% CI [1.0, 2.9]); and no history of sexually transmitted diseases (OR=1.6, 95% CI [1.0, 2.5]). Risk score weights were 5 for an elevated vaginal pH and 1 otherwise. The sensitivity and specificity of screening women with scores > or =4 were both 77%; this would involve screening 33% of patients.

CONCLUSION

Approximately 80% of our BV cases were asymptomatic, emphasizing the need for objective risk assessment. Using six factors, clinicians can identify pregnant women at risk for BV.

Occurrence and antimicrobial susceptibility of Ureaplasma parvum (Ureaplasma urealyticum biovar 1) and Ureaplasma urealyticum (Ureaplasma urealyticum biovar 2) from patients with adverse pregnancy outcomes and normal pregnant women

A recent phylogenetic analysis of Ureaplasma urealyticum resulted in the proposal to divide their 2 biovars into species. We used PCR to compare the distribution of species and the presence of the tet(M) and int-Tn resistance determinants in 63 strains of Ureaplasma spp. isolated from the amniotic fluid of patients with an adverse pregnancy outcome and in 22 strains obtained from the lower genital tract of healthy pregnant women. We also determined the antimicrobial susceptibility of the organisms to erythromycin and tetracycline. U. parvum was the most frequent Ureaplasma species detected in our study. Thus, 50/63 (79.4%) invasive isolates and 17/22 (77.3%) lower genital tract isolates corresponded to U. parvum, whereas 12/63 (19%) invasive isolates and 4/22 (18.2%) non-invasive strains corresponded to U. urealyticum. A mixture of species was found in 2 women. We found no significant differences in the antimicrobial susceptibility of isolates according to species or origin of isolation. Sixty-two strains of Ureaplasma spp. (74.7%) were susceptible to erythromycin, and 21 strains (25.3%) were intermediately susceptible. Sixty-eight isolates (81.9%) were susceptible to tetracycline, 2 strains (2.4%) were intermediate and 13 strains (15.7%) were resistant. DNA sequences related to the tet(M) determinant and the int-Tn gene were found in all tetracycline-resistant isolates.

The association between Porphyromonas gingivalis-specific maternal serum IgG and low birth weight

BACKGROUND

In Alabama, low birth weight (LBW) infants are about 20 times more likely to die before their first birthday compared to normal birth weight infants. While the rate of LBW has been consistently higher among African Americans compared to whites, there has been a gradual increase in LBW for both African Americans and whites over the last 15 years. In an attempt to identify modifiable risk factors for LBW, we have previously reported that a pregnant woman's poor periodontal health may be an independent risk factor for low birth weight.

METHODS

A predominantly African American and socioeconomically homogeneous group of 448 women was followed from the second trimester of their first pregnancy. Thirty-nine LBW cases were observed at the end of follow-up. Using 17 preterm LBW cases and 63 randomly selected controls from the above cohort, the periodontal pathogen-specific maternal serum IgG levels during the second trimester of pregnancy were evaluated in relation to birth weight of the infant, while controlling for known risk factors for LBW.

RESULTS

Porphyromonas gingivalis (P.g.)-specific maternal serum IgG levels were higher in the LBW group (mean 58.05, SE = 20.00 microg/ml) compared to the normal birth weight (NBW) group (mean 13.45, SE = 3.92 microg/ml; P= 0.004). Women with higher levels of P.g.-specific IgG had higher odds of giving birth to LBW infants (odds ratio [OR] = 4.1; 95% confidence interval [CI] for odds ratio = 1.3 to 12.8). This association remained significant after controlling for smoking, age, IgG levels against other selected periodontal pathogens, and race.

CONCLUSIONS

Low birth weight deliveries were associated with a higher maternal serum antibody level against P. gingivalis at mid-trimester.

Gardnerella vaginalis isolated from patients with bacterial vaginosis and from patients with healthy vaginal ecosystems

The differences in the phenotype and genotype of Gardnerella vaginalis isolates from patients with bacterial vaginosis (BV) and from patients without BV are unknown. In our study, 43 isolates of G. vaginalis were examined for biotype (hippurate hydrolysis, lipase, and beta-galactosidase activity), sensitivity to metronidazole, and genotype. Of the 117 women visiting the gynecology clinic at Rush-Presbyterian-St. Luke's Medical Center who were included in the study, 27.4% were found to have BV. G. vaginalis was found in samples from 87.5% of women with BV, from 34.0% of women with intermediate BV, and from 26.4% of women with healthy vaginal ecosystems. Among patients with G. vaginalis, biotypes 7 and 8 were isolated from 32% and 20% of patients, respectively. Biotype 5 was predominantly associated with a healthy vaginal ecosystem (P=.0004). Biotypes 5 and 7 were the most resistant to metronidazole. No specific phenotype or genotype of G. vaginalis causes BV.

Bacterial vaginosis in early pregnancy and adverse pregnancy outcome

OBJECTIVE

To assess the prevalence of bacterial vaginosis (BV) in asymptomatic pregnant women and its association with preterm birth (PTB) and premature rupture of membranes (PROM).

METHODS

In a cohort study 1,006 pregnant women between 16-28 weeks' gestation were screened for BV (Nugent's criteria) and for lower genital tract infection. Women were followed to confirm pregnancy outcome. Data were analyzed using STATA software. Univariate and multivariate methods were used to investigate the association between bacterial vaginosis and adverse pregnancy outcome.

RESULTS

Prevalence of BV was 11.53%. Baseline characteristics were similar for both groups, 6.8% women were lost to follow-up. Incidence of PTB was higher in BV positive women compared to BV negative women (p = 0.001). On multiple logistic regression (MLR), BV was associated with an increased risk of PTB (p = 0.001) and PROM (p = 0.001), other correlates being previous PTB (p = 0.003) and the presence of enteropharyangeal organisms in vagina (p = 0.03). BV accounted for 82.53% of the attributable risk for PTB.

CONCLUSION

Presence of BV in early pregnancy is associated with an increased risk of PTB and PROM. Multicentric interventional study is recommended.

Is there an interaction between cervical length and cervical microbiology in the pathogenesis of preterm labour?

Transvaginal ultrasound of the cervix is increasingly used to estimate cervical length during pregnancy. Initially used to determine a possible need for cervical suture, the technique has been shown to be of value in the prediction of preterm delivery In addition, bacterial vaginosis has been shown to be associated with an increased risk of preterm delivery. We hypothesised that shortening of the cervix and potential cervical pathogens, in particular the presence of bacterial vaginosis, act synergistically in the pathogenesis of premature labour. Three hundred and sixteen women were recruited for prospective longitudinal follow-up, with both transvaginal ultrasound and cervical bacteriology performed at approximately 18 and 28 weeks gestation. A strong correlation was found between a shortened cervix and preterm delivery (p<0.02 at 18 weeks; p<0.001 at 28 weeks). Women with both a short cervix and cervical pathogens had the highest risk of preterm delivery (43%), although not significantly greater than a short cervix with normal cervical flora (31% preterm delivery). In the presence of a normal cervical length, preterm delivery rates in the presence of normal flora and potential cervical pathogens were much lower (9% and 5% respectively).

Diagnostic value of the papanicolaou smear in lower genital tract infections during pregnancy

OBJECTIVES

To evaluate the diagnostic value of the Pap smear in lower genital tract infections during pregnancy.

MATERIALS AND METHODS

A total of 190 pregnant women were examined in the Lower Genital Tract and Colposcopy clinics of the Obstetrics Division at the University Hospital de Clínicas "José de San Martín" of University of Buenos Aires from April to August 1997. Samples were taken from the vaginal fornix for microbiologic study and from the exocervix for Pap smear. Both the sensitivity and specificity test of the Pap smear for diagnosing lower genital tract infections were calculated considering the microbiologic study as the reference standard.

RESULTS

The sensitivity of the Pap smear for Candida spp., bacterial vaginosis and Trichomonas vaginalis compared with microbiologic study was 50, 81, and 78, respectively. The specificity for the same study was 96%, 93%, and 100%, respectively.

CONCLUSIONS

Pap smear for diagnosing lower genital tract infections is useful when positive results are found for these infections because of its high specificity.

Infection and preterm birth: evidence of a common causal relationship with bronchopulmonary dysplasia and cerebral palsy

Subclinical genital tract infection has been clearly established as a significant cause of spontaneous preterm birth, particularly in early gestations. Bacterial vaginosis organisms rank highly among the pathogens involved in preterm labour and there is considerable beneficial evidence from the use of prophylactic antibiotics for women at high risk of preterm birth. The pathogenesis involves activation of macrophages and the generation of pro-inflammatory cytokines. Bronchopulmonary dysplasia is seen in the most immature of survivors and appears to be secondary to interruption of normal development and maturation of the lungs. The link between chorioamnionitis and lung injury in utero and subsequent development of bronchopulmonary dysplasia has now been substantiated. Exposure to pro-inflammatory cytokines is implicated in the impairment of the fetal lung. A significant body of evidence supports the association between chorioamnionitis, periventricular leukomalacia and cerebral palsy. Biological mechanisms that explain the association between chorioamnionitis and fetal brain injury involve pro-inflammatory cytokines. Similarity in the pattern of expression of cytokines suggests a common pathway for the initiation of preterm labour and also injury to the lung and the central nervous system of the fetus.

Bacterial vaginosis in pregnancy

Bacterial vaginosis is a clinical condition caused by replacement of the normal hydrogen peroxide producing Lactobacillus sp. in the vagina with high concentrations of characteristic sets of aerobic and anaerobic bacteria. Bacterial vaginosis is the most prevalent cause of vaginal discharge or malodor, although 50 percent of women who meet the criteria for this condition are asymptomatic. Bacterial vaginosis is reported in 10 to 41 percent of women, and new evidence has shown association with maternal and fetal morbidity. Studies have shown that spontaneous abortion, preterm labor, premature birth, preterm premature rupture of the membranes, amniotic fluid infection, postpartum endometritis, and postcesarean wound infections are increased because of infection with bacterial vaginosis during pregnancy. Clinical trials demonstrated important reductions in many of these adverse events with appropriate screening and antimicrobial treatment protocols. New low-cost, diagnostic, point-of-care screening tools are available for rapid screening of patients, affording the physician the opportunity to potentially make a dramatic clinical and cost impact in preventing preterm birth and the costly sequelae of prematurity. Practicing physicians need to be aware of current guidelines for screening and treating pregnant patients for bacterial vaginosis. The authors recommend that all pregnant women be screened and treated with the Centers for Disease Control and Prevention (CDC-P) recommended oral regimens early in pregnancy. Each treated women should be evaluated for "test of cure" 1 month after treatment. Mothers likely to benefit from "screen and treat" approaches include 1) those with the highest concentrations of genital anaerobes and mycoplasmas, 2) women with prior preterm birth or who have low body mass (BMI < 19.8 kg/m2), 3) those with evidence of endometritis before pregnancy, and 4) those who are treated with oral agents effective for both presumed intrauterine mycoplasmas and other bacterial vaginosis flora (i.e., oral clindamycin or erythromycin and metronidazole).

Is antenatal group B streptococcal carriage a predictor of adverse obstetric outcome?

OBJECTIVES

While early-onset neonatal GBS sepsis is positively associated with premature birth and prolonged rupture of membranes, there is debate in the literature as to whether maternal GBS colonization is a predictor of adverse obstetric outcome. This is a critical issue to resolve for appropriate management (expectant vs. interventional management) of the patient presenting with premature rupture of membranes, who has no overt signs of sepsis, but who is colonized with GBS.

METHODS

Since 1981 it has been hospital policy to screen all public patients antenatally for genital carriage of GBS by collection of a low vaginal swab at 28-32 weeks. All patients colonized with GBS antenatally are given penicillin as intrapartum chemoprophylaxis. Review of all GBS-colonized antenatal patients for a 12-month period (580 of 4,495 patients) and a randomized (every fourth consecutive antenatal patient) number of noncolonized patients (958) was made. Lower vaginal GBS colonization and other risk factors for preterm delivery were assessed using univariate and multivariate generalized linear modeling.

RESULTS

In the study group, the maternal GBS colonization rate was 12.9%. When cofounding variables were controlled in a multivariate analysis, the association between antepartum GBS colonization and preterm labor and preterm rupture of membranes was not significant.

CONCLUSION

Maternal antenatal carriage of GBS does not predict preterm labor. Therefore it is appropriate that expectant management occur for a GBS-colonized woman who ruptures her membranes, is not in labor, and has no evidence of sepsis.

Intrauterine infection and spontaneous midgestation abortion: is the spectrum of microorganisms similar to that in preterm labor?

OBJECTIVE

To determine whether microorganisms associated with intrauterine infection and preterm labor play a contributing role in midgestation abortion.

METHODS

A 4 year retrospective review of spontaneous midgestation abortions for which autopsy and microbiological cultures of placental and fetal tissue were performed was conducted for a tertiary obstetrics hospital, which included a regional referral service for perinatal and fetal pathology. One hundred twenty-nine spontaneously delivered, nonmacerated, midgestation fetuses or stillbirths (of between 16 and 26 weeks' gestation) and placentas were examined and cultured for aerobic and anaerobic bacteria, yeasts, and genital mycoplasmas.

RESULTS

Microorganisms were recovered in 85 (66%) cases (57% placentas, 49% fetuses). Among the culture positive cases, 81% had histological chorioamnionitis, 28% fetal pneumonitis, 38% clinical signs of infection, and 62% ruptured membranes at the time of miscarriage. These differed significantly from culture-negative cases (44%, 5%, 13%, and 34%, respectively). Group B streptococcus (GBS) was the most significant pathogen, recovered in 21 cases, 13 as the sole isolate, 94% with chorioamnionitis, and 47% in women with intact membranes. Escherichia coli and Ureaplasma urealyticum (22 and 24 cases, respectively) occurred mostly as mixed infections, with ruptured membranes. GBS, MU urealyticum, and Streptococcus anginosus group were individually associated with chorioamnionitis, Bacteroides/Prevotella and S. anginosus with fetal pneumonitis. The spectrum of microorganisms was similar to that in preterm labor at later gestations; however, GBS appeared to be the most significant pathogen in midgestation miscarriage, especially with intact membranes.

CONCLUSIONS

Unsuspected intrauterine infection underlies many spontaneous midgestation abortions. GBS is a key pathogen in this setting.

Maturation of spontaneous and agonist-induced uterine contractions in the peripartum mouse uterus

This study tested the hypothesis that the uterus achieves maximum contractile capabilities before the onset of labor. Basal and agonist-stimulated contractions were assessed in uterine strips on Day 15 or 18 of pregnancy, the day of parturition, or 1 day postpartum (n = 4-13 per group). Spontaneous contractions were evident in all groups (n = 4-13 per gestational group); contraction frequency was greater in peripartum groups than in virgin controls ( approximately 4.6 versus 2.8/200 sec). Peak amplitude was nearly 9-fold higher on Days 15 and 18 and over 30-fold higher in the postpartum and 1 day postpartum groups than in nonpregnant mice. Maximum frequency and peak amplitude were achieved in response to 10(-6) to 10(-8) M oxytocin or arginine vasopressin (OT(max) or AVP(max)). Frequency of contractions in response to OT(max) peaked on Day 18 and then declined. Contraction amplitude increased 5-fold on Day 15, declined on the day of birth (equivalent to nonpregnant level), then rebounded to peak on postpartum Day 1. AVP(max) similarly increased frequency and amplitude of contractions, except that maximum contraction amplitude occurred postpartum. Thus, an endogenous oscillator, residing in the uterus, sustains high basal and agonist-induced contraction frequency during pregnancy. Although acceleration of this pacemaker occurred before term, the data suggest that peripartum increases in contraction amplitude characterize the transition to the powerful synchronous contractions of parturition.

Microbial interactions in the vaginal ecosystem, with emphasis on the pathogenesis of bacterial vaginosis

During bacterial vaginosis (BV), populations of lactobacilli which are generally dominant in the vagina of overtly healthy women are replaced by other facultative and anaerobic microorganisms. Some Lactobacillus strains produce hydrogen peroxide and all produce lactic acid; however, the antagonistic role of these metabolites in vivo remains controversial. Positive interactions among BV-associated organisms may contribute to the pathogenesis of BV and its sequelae.

A commensal symbiosis between Prevotella bivia and Peptostreptococcus anaerobius involves amino acids: potential significance to the pathogenesis of bacterial vaginosis

In both batch and continuous culture, Peptostreptococcus anaerobius was able to grow in vaginal defined medium with Prevotella bivia, but not in pure culture. Growth of P. anaerobius was increased by 238% (P < 0.001) in peptone-supplemented vaginal defined medium conditioned by prior growth of P. bivia. Analysis of P. bivia culture supernatants showed a net accumulation of amino acids and subsequent growth of P. anaerobius in the conditioned supernatants resulted generally in amino acid utilization. Supplementation of peptone-supplemented vaginal defined medium with amino acids in concentrations similar to those available after prior growth with P. bivia were growth-stimulatory (246%, P=0.006) for P. anaerobius. Increased availability of amino acids by P. bivia is proposed as a mechanism to support the observed in vitro commensal symbiosis between P. bivia and P. anaerobius.

Bacterial vaginosis: association with adverse pregnancy outcome

Bacterial vaginosis is the most common lower genital tract infection encountered among women of reproductive age. This condition can best be considered as a vaginal syndrome associated with an alteration of the normal vaginal flora rather than an infection specific to any one microorganism. Bacterial vaginosis is a clinical condition with a complex microbiology that is characterized by a reduced concentration of a normally abundant Lactobacillus species along with high concentrations of gram-negative and anaerobic bacteria, particularly, Gardnerella vaginalis and Mobiluncus, Bacteroides, Prevotella, and Mycoplasma species. The exact make up of the microorganisms and their relative concentration vary among women who have this condition. Although it was previously regarded as a harmless condition, recent work has linked bacterial vaginosis to numerous upper genital tract complications such as preterm labor and preterm delivery, preterm premature rupture of the membranes, chorioamnionitis, and postpartum endometritis. The findings from recent prospective randomized trials suggest that treatment of bacterial vaginosis in certain women who are at high risk for preterm delivery decreases the rate of preterm birth.

Preterm birth: associations with genital and possibly oral microflora

Opportunistic pathogenic microbes are indigenous to the female lower genital tract and etiologic in many types of pelvic infections and, apparently, a portion of preterm birth (PTB) cases. Bacterial vaginosis (BV) is a clinical syndrome based on an altered genital microflora in which Gardnerella vaginalis; anaerobic species primarily among Prevotella, Porphyromonas, Bacteroides, Peptostreptococcus, and Mobiluncus; Mycoplasma hominis; and Ureaplasma urealyticum become predominant in vaginal secretions. This BV complex of microbes, compared to a normal vaginal microflora dominated by facultative lactobacilli, is associated with significantly increased risks for preterm labor, preterm premature rupture of membranes, PTB, and other perinatal infectious complications. Pathogenetic mechanisms include an ascending route of infection and/or inflammatory process due to microbial products and maternal and/or fetal response(s) with production of prostaglandins and cytokines. In the presence of periodontal disease, oral opportunistic pathogens and/or their inflammatory products also may have a role in prematurity via a hematogenous route. Fusobacterium nucleatum, a common oral species, is the most frequently isolated species from amniotic fluid cultures among women with preterm labor and intact membranes. Also, the species and subspecies of fusobacteria identified from amniotic fluid most closely match those reported from healthy and diseased subgingival sites, namely F. nucleatum subspecies vincentii and F. nucleatum subspecies nucleatum, compared to strains identified from the lower genital tract. Although these fusobacteria also could be acquired through cunnilingus from a partner, new data associating maternal periodontal disease with preterm low birth weight taken with the isolation of F. nucleatum, Capnocytophaga, and other oral species from amniotic fluid support further study of a possible additional route, oral-hematogenous, to PTB.

Potential pathogenic mechanisms of periodontitis associated pregnancy complications

During normal pregnancy, maternal hormones and locally acting cytokines play a key role in regulating the onset of labor, cervical ripening, uterine contraction, and delivery. Maternal infections during pregnancy have been demonstrated to perturb this normal cytokine and hormone-regulated gestation, sometimes resulting in preterm labor, preterm premature rupture of membranes, and preterm low birth weight (PLBW), i.e., < 2,500 g and < 37 weeks of gestation. Our research focus has been to determine whether periodontal infections can provide sufficient challenge to the mother to trigger PLBW. New experiments from 48 case-control subjects have measured gingival crevicular fluid (GCF) levels of PGE(2) and IL-1-beta to determine whether mediator levels were related to current pregnancy outcome. In addition, the levels of 4 periodontal pathogens were measured by using microbe-specific DNA probes. Results indicate that GCF-PGE(2) levels are significantly higher in PLBW mothers, as compared with normal birth weight (NBW) controls (131.4 +/- 21.8 vs. 62.6 +/- 10.3 [mean +/- SE ng/mL], respectively, at P = 0.02). Furthermore, within primiparous PLBW mothers, there was a significant inverse association between birth weight (as well as gestational age) and GCF-PGE(2) levels at P = 0.023. These data suggest a dose-response relationship for increasing GCF-PGE(2) as a marker of current periodontal disease activity and decreasing birth weight. Microbial data indicate that 4 organisms associated with mature plaque and progressing periodontitis--bacteroides forsythus, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, and Treponema denticola--were detected at higher levels in PLBW mothers, as compared to NBW controls. These data suggest that biochemical measures of maternal periodontal status and oral microbial burden are associated with current PLBW.

Poor periodontal health of the pregnant woman as a risk factor for low birth weight

In both developed and developing countries, low birth weight (LBW) has a tremendous impact on both the health care system and the individual families affected. This warrants the continuous search for risk factors for LBW that are amenable to prevention. Can poor oral health of the pregnant woman be one such factor? In a 1:1 matched case-control study (N = 55 pairs), we evaluated the hypothesis that poor oral health of the pregnant woman is a risk factor for LBW. The effect of periodontal and dental caries status of the woman at the time of delivery on the birth weight of the infant was evaluated by using conditional logistic regression analyses, while controlling for known risk factors for LBW. Mothers of LBW infants were shorter, less educated, married to men of lower occupational class, had less healthy areas of gingiva and more areas with bleeding and calculus, and gained less weight during the pregnancy. Conditional logistic regression analyses indicated that mothers with more healthy areas of gingiva (OR = 0.3, 95% CI = 0.12 - 0.72) and those who were taller (OR = 0.86, 95% CI = 0.75 - 0.98) had a lower risk of giving birth to an LBW infant. Risk of LBW was higher in mothers who had no or late prenatal care (OR = 3.9, 95% CI = 1.24 - 12.2). We conclude that poor periodontal health of the mother is a potential independent risk factor for LBW.

Eicosanoids in periodontal diseases: potential for systemic involvement

The potential application of gingival crevicular fluid (GCF) levels of prostaglandin E2 (PGE2) for predicting periodontal disease severity and reflecting disease activity has been described by several investigators. The potential application of GCF levels of PGE2 for predicting amniotic fluid levels of PGE2, and thereby estimating risk of preterm low birth weight, has not been explored until recently. The fact that intraamniotic levels of many inflammatory mediators, such as prostaglandin E2, increase during pregnancy and peak at delivery suggests that these mechanisms play an important role in normal physiologic parturition. There is increasing evidence to suggest that the presence of a subclinical endogenous Gram-negative infection of periodontal disease may present a systemic challenge sufficient to initiate the onset of premature labor, either as a source of lipopolysaccharide (LPS, endotoxin) and/or through stimulation of secondary inflammatory mediators such as PGE2 and interleukin 1 beta (IL-1 beta). This pilot investigation determines associations among the levels of PGE2 in gingival crevicular fluid, within serum, and within amniotic fluid of 18 women who were undergoing routine amniocentesis during early midtrimester, in an attempt to reveal new baseline data regarding the relationship between periodontal inflammatory mediators and intraamniotic mediators during normal parturition. Full-mouth periodontal examinations were performed and samples of GCF, serum and amniotic fluid were collected from each subject for the quantitative assessment of PGE2 by radioimmunoassay (RIA). Results of a pairwise regression analysis model reveal that PGE2 levels within the GCF are positively associated with intraamniotic PGE2 levels at the P = 0.018 level of significance. Thus, gingival crevicular levels of PGE2 may be used to provide an indirect estimate of the amniotic fluid levels of PGE2.

Impact of metronidazole therapy on preterm birth in women with bacterial vaginosis flora (Gardnerella vaginalis): a randomised, placebo controlled trial

OBJECTIVE

To ascertain whether metronidazole treatment of women with a heavy growth of Gardnerella vaginalis during mid-pregnancy would reduce the risk of spontaneous preterm birth.

DESIGN

A multicentre, randomised, placebo-controlled trial.

SETTING

Four metropolitan hospitals.

PARTICIPANTS

Eight hundred and seventy-nine singleton women with a heavy growth of G. vaginalis or Gram stain indicative of bacterial vaginosis at 19 weeks of gestation.

INTERVENTIONS

Oral metronidazole (400 mg) or placebo twice daily for two days at 24 weeks of gestation, and at 29 weeks if G. vaginalis found in test-of-cure swab four weeks after treatment.

MAIN OUTCOME MEASURES

Spontaneous preterm birth less than 37 weeks.

RESULTS

Intention-to-treat analysis showed no difference between metronidazole and placebo groups in overall preterm birth (31/429 [7.2%] vs 32/428 [7.5%]) or spontaneous preterm birth (20/429 [4.7%] vs 24/428 [5.6%]). Among the 480 women with bacterial vaginosis treatment had no effect on spontaneous preterm birth (11/242 [4.5%] vs 15/238 [6.3%]). In the subset of 46 women with a previous preterm birth, women in the metronidazole group showed a significant reduction in spontaneous preterm birth (2/22 [9.1%] vs 10/24 [41.7%], OR 0.14, 95% CI 0.01-0.84). A treatment effect was also found in compliant women with a previous preterm birth and bacterial vaginosis (0/14 [0%] vs 6/17 [35.3%], OR 0.0, 95% CI 0.0-0.94).

CONCLUSION

Metronidazole treatment of women with a heavy growth of G. vaginalis or bacterial vaginosis did not reduce the preterm birth rate. Among women with a previous preterm birth, treatment reduced the risk of spontaneous preterm birth. Further studies are required to confirm these findings.

Treatment of Gardnerella vaginalis infection

This review of the antibiotic sensitivity pattern of Gardnerella vaginalis culture isolates shows that the drugs found sensitive to G. vaginalis cultures include the new antimicrobial agents- ciprofloxacin, cefuroxine and ceftazidine, and some older antibiotics- ceftriaxone, cloxacillin, erythromycin, chloramphenicol and metranidazole. Streptomycin and augmentin showed intermediate sensitivity while penicillin, ampicillin, tetracycline and gentamycin exhibited resistance to G. vaginalis isolates. Metronidazole is currently the first-line drug of choice for the treatment of G. vaginalis and its related infections because of its effectiveness not just against G. vaginalis but also against anaerobes. It can be administered orally, parenterally and intravaginally as gel or sponge. The advantages and drawbacks to the use of these G. vaginalis - sensitive drugs, and the place of alternative drugs in the management of G. vaginalis - associated infections are discussed.

Comparison of Gram-stained smears prepared from blind vaginal swabs with those obtained at speculum examination for the assessment of vaginal flora

OBJECTIVE

To determine whether Gram-stained smears obtained from blind vaginal swabs could be used reliably for the assessment of the vaginal flora.

DESIGN

A prospective, blind comparative study.

SETTING

The antenatal clinic of a district general hospital.

PARTICIPANTS

Eighty-eight women examined and screened for the presence of bacterial vaginosis during their first antenatal clinic visit. Two smears were obtained for each woman, the first prepared from a vaginal swab taken blindly and the second at speculum examination. The smears were Gram-stained and classified according to the Nugent score: Grade 1 (normal), Grade 2 (intermediate), Grade 3 (bacterial vaginosis).

RESULTS

Eight of the 88 pregnant women were identified as having bacterial vaginosis on the basis of the smear taken at speculum examination, and these were correctly identified as having bacterial vaginosis by smears prepared from the blindly taken swab. This gives the blind vaginal swab technique for detecting bacterial vaginosis a sensitivity and specificity of 100% when compared with swabbing at speculum examination. The flora of two women were graded as intermediate, and of 75 as normal by both techniques. Only in three cases was there a disparity between the two techniques, a difference that was not statistically significant (kappa = 0.8546, 95% CI 0.6945 to 1.0).

CONCLUSIONS

Vaginal smears prepared from correctly taken blind vaginal swabs can be used to assess the vaginal flora and screen for bacterial vaginosis. This method could be used in epidemiological studies of bacterial vaginosis in the general population and for screening antenatal populations for abnormal vaginal flora.

Periodontal infection as a possible risk factor for preterm low birth weight

Peridontal diseases are gram-negative anaerobic infections that can occur in women of childbearing age (18 to 34 years). In the present investigation we sought to determine whether the prevalence of maternal periodontal infection could be associated with preterm low birth weight (PLBW), controlling for known risk factors and potential covariates. A case-control study of 124 pregnant or postpartum mothers was performed. PLBW cases were defined as a mother with a birth of less than 2,500 g and one or more of the following: gestational age < 37 weeks, preterm labor (PTL), or premature rupture of membranes (PROM). Controls were normal birth weight infants (NBW). Assessments included a broad range of known obstetric risk factors, such as tobacco use, drug use, alcohol consumption, level of prenatal care, parity, genitourinary infections, and nutrition. Each subject received a periodontal examination to determine clinical attachment level. PLBW cases and primiparous PLBW cases (n = 93) had significantly worse periodontal disease than the respective NBW controls. Multivariate logistic regression models, controlling for other risk factors and covariates, demonstrated that periodontal disease is a statistically significant risk factor for PLBW with adjusted odds ratios of 7.9 and 7.5 for all PLBW cases and primiparous PLBW cases, respectively. These data indicate that periodontal diseases represent a previously unrecognized and clinically significant risk factor for preterm low birth weight as a consequence of either PTL or preterm PROM.

The pathobiology of premature rupture of membranes

Premature rupture of membranes arises from what are likely multifaceted and multistep pathogenic pathways. Pathophysiological processes may involve both endogenous and exogenous fetal and maternal factors. This article reviews and analyzes information regarding, first, the form and function of fetal membranes; second, how membranes physically fail (rupture) at term and preterm gestations; and third, evaluates if we can reduce risks of rupture using physiological understanding and evidence-based clinical studies.

Bacterial vaginosis: prevalence in an Italian population of asymptomatic pregnant women and diagnostic aspects

The present study has been carried out with the main objective of determining the prevalence rate of bacterial vaginosis (BV) in a population of asymptomatic pregnant women (8th to 9th month of pregnancy). Out of a total 1,441 patients examined BV was found to be present in 70 (4.9%). The diagnosis was made when an analysis of the vaginal discharge revealed the simultaneous presence of at least three out of four of the following laboratory indices: (1) direct Gram stain positive (bacterial flora mixed with Gram-negative coccobacilli and variable-gram predominant over the lactobacillus flora); (2) pH > 4.5; (3) positive odour test with KOH 10%; (4) presence of clue cells. After a discussion of the principal laboratory and clinical signs presently used for the diagnosis of BV, the authors suggest the exclusion of the evaluation of the appearance of the vaginal discharge from the standard diagnostic criteria. Further, three diagnostic methods are hypothesized for use in different settings.

Very preterm birth--a regional study. Part 1: Maternal and obstetric factors

OBJECTIVE

To ascertain the demographic, pregnancy and obstetric factors associated with the delivery of a liveborn very preterm infant ( < 33 weeks of gestation) and to investigate any differences in these factors between identifiable aetiological groups.

DESIGN

Cohort analytical study.

SETTING

King Edward Memorial Hospital for Women (KEMH), Western Australia.

MAIN VARIABLES EXAMINED

Maternal demographic and obstetric history, primary complication associated with delivery, obstetric management and mode of delivery.

RESULTS

Six hundred and eight women who were delivered of 693 liveborn very preterm infants in Western Australia between 1.1.90 and 31.12.91, representing 1.22% of all women who were delivered of a liveborn infant in those years. Singleton pregnancy occurred in 517 (85%) and 541 (89%) were delivered in KEMH. Mean maternal age was 28 years with an excess of mothers less than 20 years of age and older than 34 years compared with the statewide perinatal data. Pre-eclampsia (n = 128, 21.1%), preterm prelabour rupture of membranes (n = 148, 24.3%), idiopathic preterm labour (n = 195, 30.4%) and antepartum haemorrhage (n = 111, 18.3%) were associated with 94.1% of deliveries. These proportions varied with plurality and period of gestation. Demographic details, use of antenatal steroids, exposure to labour and caesarean section delivery differed between mothers depending on the primary complication. Overall 322 (53.0%) received antenatal steroids and 297 (48.8%) were delivered by caesarean section. Factors associated with decreased use of steroids were gestational age of less than 27 weeks (odds ratio (OR) 0.54; 95% CI 0.36-0.83), preterm prelabour rupture of the membranes (OR 0.48; 95% CI 0.29-0.78) and idiopathic preterm labour (OR 0.56; 95% CI 0.35-0.91). Factors associated with increased use of steroids were multiple pregnancy (OR 1.70; 95% CI 1.02-2.81) and pre-eclampsia (OR 1.87; 95% CI 1.09-3.19).

CONCLUSIONS

These very preterm deliveries account for only a small proportion of all deliveries. There are differences in the mother's demographic history, obstetric management and delivery depending on the primary aetiological factor.

Association between bacterial vaginosis and preterm delivery of a low-birth-weight infant. The Vaginal Infections and Prematurity Study Group

BACKGROUND

Bacterial vaginosis is believed to be a risk factor for preterm delivery. We undertook a study of the association between bacterial vaginosis and the preterm delivery of infants with low birth weight after accounting for other known risk factors.

METHODS

In this cohort study, we enrolled 10,397 pregnant women from seven medical centers who had no known medical risk factors for preterm delivery. At 23 to 26 weeks' gestation, bacterial vaginosis was determined to be present or absent on the basis of the vaginal pH and the results of Gram's staining. The principal outcome variable was the delivery at less than 37 weeks' gestation of an infant with a birth weight below 2500 g.

RESULTS

Bacterial vaginosis was detected in 16 percent of the 10,397 women. The women with bacterial vaginosis were more likely to be unmarried, to be black, to have low incomes, and to have previously delivered low-birth-weight infants. In a multivariate analysis, the presence of bacterial vaginosis was related to preterm delivery of a low-birth-weight infant (odds ratio, 1.4; 95 percent confidence interval, 1.1 to 1.8). Other risk factors that were significantly associated with such a delivery in this population were the previous delivery of a low-birth-weight infant (odds ratio, 6.2; 95 percent confidence interval, 4.6 to 8.4), the loss of an earlier pregnancy (odds ratio, 1.7; 1.3 to 2.2), primigravidity (odds ratio, 1.6; 1.1 to 1.9), smoking (odds ratio, 1.4; 1.1 to 1.7); and black race (odds ratio, 1.4; 1.1 to 1.7). Among women with bacterial vaginosis, the highest risk of preterm delivery of a low-birth-weight infant was found among those with both vaginal bacteroides and Mycoplasma hominis (odds ratio, 2.1; 95 percent confidence interval, 1.5 to 3.0).

CONCLUSIONS

Bacterial vaginosis was associated with the preterm delivery of low-birth-weight infants independently of other recognized risk factors.

Delayed interval delivery after intrauterine infection and immature birth of twin 1--a case report and literature review

We report a case of delayed interval delivery in a twin pregnancy complicated by rupture of membranes, intrauterine infection and birth of one twin at 21 weeks gestation. Tocolysis combined with antibiotics and corticosteroids successfully prolonged pregnancy for 73 days, allowing the second twin to mature and reach viability. At 31.5 weeks gestation, a 1890 g healthy male neonate was born with good Apgar scores. His postnatal course was uneventful. A literature review of several other cases of delayed interval delivery is presented. When multifetal pregnancies are complicated by immature birth of one fetus, delayed interval delivery may offer survival chances and favourable outcome for the remaining fetus(es).

Prevention of preterm birth

Preterm labour and delivery remain a major cause of perinatal morbidity, mortality and long-term adverse neurodevelopmental outcome. An effective primary prevention strategy is desirable, but current approaches appear largely ineffective at present. Understanding the aetiology of the onset of preterm labour continues to improve with the recognition of the role played by subclinical infection in a significant proportion of cases. The investigation of hormonal influences in the aetiology of preterm labour is at an early stage, but there appears to be a relationship between raised serum relaxin concentrations and preterm delivery (Petersen et al, 1992). The naturally occurring phospholipase A2-inhibitor gravidin, believed to be important in pregnancy maintenance, is found in a reduced concentration in women delivering preterm (Wilson, 1993). The relationship between hormonal levels, socio-economic influences, subclinical infection and actual preterm labour and delivery remains to be established. Secondary prevention with tocolysis remains unsatisfactory, owing to the low therapeutic index of currently available agents and their varied maternal and neonatal adverse effects. The investigation of newer tocolytic agents remains a worthwhile pursuit, whilst the underlying aetiology of preterm labour and effective prevention remains to be elucidated. The widespread recognition of the benefits of antenatal corticosteroid administration and subsequent adoption into clinical practice has reduced, and will continue to reduce, the morbidity associated with preterm birth while newer methods of accelerating fetal maturation are explored and applied in clinical practice.

Untreated cervical infections, chorioamnionitis and prematurity

OBJECTIVE

To examine the relationship of endocervical pathogens and cervicitis with the development of chorioamnionitis, premature rupture of membranes (PROM) and prematurity.

METHODS

Three groups of pregnant women were included in the study: group A, controls with no evidence of cervicitis; group B, women with cervicitis due to pathogenic bacteria, who had been treated; and group C, women with untreated cervicitis who had not followed the prescribed therapy. Endocervical samples were cultured and aerobic and anaerobic bacteria isolated to examine the correlation of cervicitis with chorioamnionitis, PROM and prematurity.

RESULTS

There was a significantly higher incidence of prematurity in women with untreated cervicitis (group C). Mixed endocervical pathogens were most often involved (36.3%). A significantly higher number of endocervical pathogens were isolated in cases of chorioamnionitis (P < 0.001). Prematurity was seen in 39.6% of cases of chorioamnionitis. Prematurity was also more common in women with PROM (42.1%) than in those with intact membranes (11.8%).

CONCLUSION

It is concluded that untreated endocervical infections are an etiological factor of chorioamnionitis, PROM and prematurity.

Bacterial vaginosis in a district genitourinary medicine department: significance of vaginal microbiology and anaerobes

The aim of this study was to correlate the significance of vaginal microbiology, in particular its anaerobic component, to the presence of bacterial vaginosis (BV), and to review the clinical criteria used in the diagnosis of this condition. Ninety-two female patients who received routine STD screening were studied. After routine history, presence and character of vaginal discharge and vaginal pH were noted, an amine test performed, and a wet stain observed microscopically. Routine Gram stain smears and cultures were prepared. BV was diagnosed clinically in 28 (30%) of our sample, and Gardnerella vaginalis was cultured in 41 patients (45%). Both clue cells and anaerobes were closely associated with each other and both mutually exclusive with the presence of lactobacilli on Gram stain (P < 0.001). BV was found to be strongly associated with the presence of clue cells on the wet film, anaerobes and G. vaginalis. In conclusion, bacterial vaginosis is not only strongly associated with the presence of G. vaginalis in the vaginal flora, but more strongly with the presence of anaerobes. The study suggests that the microaerophile G. vaginalis is a commensal organism in a significant proportion of sexually active women. If the aerobic status of the healthy vagina is disrupted, anaerobes (including Gardnerella) will flourish, producing the clinical picture of bacterial vaginosis.

Ampicillin and metronidazole treatment in preterm labour: a multicentre, randomised controlled trial

OBJECTIVE

To ascertain whether adjuvant ampicillin and metronidazole given to women in preterm labour with intact membranes would prolong pregnancy and decrease the perinatal mortality and morbidity.

DESIGN

A multicentre, prospective, randomised controlled trial.

SETTING

Three perinatal centres serving an indigent population.

SUBJECTS

Eighty-one women in active preterm labour with otherwise uncomplicated singleton pregnancies between 26 and 34 weeks gestation or an ultrasound fetal weight estimate of 800 g to 1500 g.

INTERVENTIONS

The study group received ampicillin and metronidazole for five days. The control group received no antibiotics. In all women contractions were suppressed with hexoprenaline and indomethacin for 24 h, and betamethasone was given for fetal lung maturity.

MAIN OUTCOME MEASURES

Days gained and perinatal mortality and morbidity.

RESULTS

The study (n = 43) and control groups (n = 38) were comparable at entry. In those receiving ampicillin and metronidazole the pregnancy was significantly prolonged (median 15 days versus 2.5 days, P = 0.04) with significantly more women still pregnant after seven days (63% versus 37%, P = 0.03, OR 0.34 95% CI 0.13-0.94). Significantly more infants in the control group developed necrotising enterocolitis than in the study group (5 versus 0, P = 0.02).

CONCLUSION

Adjuvant ampicillin and metronidazole in the management of women in preterm labour with intact membranes significantly prolonged the pregnancy and decreased neonatal morbidity.

Risk of preterm delivery in pregnant women with group B streptococcal urinary infections or urinary antibodies to group B streptococcal and E. coli antigens

OBJECTIVE

To establish whether there is an association between preterm delivery and either group B streptococcal urinary infection or the presence of urinary antibodies to group B streptococcal or E. coli antigens.

DESIGN

A prospective study with urine culture and antibody measurement performed at the first antenatal visit and at 28 weeks gestation.

SETTING

Ninewells Hospital, Dundee.

SUBJECTS

Two thousand and forty-three women registering consecutively at an antenatal clinic.

MAIN OUTCOME MEASURE

Delivery at less than 37 weeks gestation.

RESULTS

No increase in preterm delivery was observed in women with positive urine cultures for group B streptococci either at booking or at 28 weeks, even when confirmed by positive repeat cultures. Preterm delivery was more common in women with elevated urinary antibodies to E. coli antigens at booking (relative risk 1.81, 95% CI 1.22-2.68, P = 0.005) and at 28 weeks (relative risk 2.36, 95% CI 1.60-3.48, P < 0.0001) and to group B streptococcal antigens at 28 weeks (relative risk 2.24, 95% CI 1.46-3.43, P = 0.0003).

CONCLUSIONS

These data do not support previous reports that positive urine cultures for group B streptococci are associated with an increased risk of preterm delivery. Our report of an association between elevated levels of urinary antibodies and preterm delivery is a new finding consistent with the possibility that a local inflammatory response to uro-genital infection may be important in stimulating the onset of preterm labour. The results suggest that screening for urinary antibodies at 28 weeks gestation might help to identify a group of women at increased risk of prematurity.

Effect of ethnic origin of mother on fetal outcome

The outcome of 11046 infants, from 20 weeks' gestation, born to mothers of different ethnic origins within one London borough has been analysed. There was no difference in perinatal death rates between the Asian and white infants. Among those with mothers from Africa and the West Indies there were overall significantly more intrauterine deaths (26.8/1000 and 20.0/1000) and neonatal deaths (8.6/1000 and 9.6/1000) than for the white mothers (intrauterine deaths 8.3/1000; neonatal deaths 3.7/1000). At less than 28 weeks', gestation specific death rates were similar in all groups and the overall higher death rates were due to an increase in the proportion of preterm deliveries among the black mothers. From 28 to 36 weeks' gestation, black infants born alive had lower neonatal death rates (7.7/1000) than the white infants (19/1000). The cause of the increased incidence of preterm labour among the black mothers is uncertain, though differences in intrauterine infection rates may be an important factor.

Bacterial vaginosis and vaginal microorganisms in idiopathic premature labor and association with pregnancy outcome

The vaginal microflora of 49 women in idiopathic preterm labor was compared with that of 38 term controls to determine whether the presence of bacterial vaginosis (BV) and/or specific microorganisms would influence the rate of preterm delivery. Demographic factors, pregnancy outcome, and reproductive history were also studied. BV, as defined by the presence of clue cells in a vaginal wet mount and characteristic microbial findings in a stained vaginal smear and vaginal culture, was more common in women with preterm labor and delivery than in controls (P < 0.01). The condition, diagnosed in 41% of women who had both preterm labor and delivery (n = 22) and in 11% each of women who had preterm labor but term delivery (n = 27) and controls, was associated with a 2.1-fold risk (95% confidence intervals, 1.2 to 3.7) for preterm birth prior to 37 weeks of gestation. BV was associated with low birth weight. Of 49 women with preterm labor, 67% (8 of 12) of women with BV were delivered of low-birth-weight neonates (< 2,500 g) compared with 22% (8 of 37) of women without the condition (P < 0.0005). The presence of hydrogen peroxide-producing facultative Lactobacillus spp. was strongly negatively associated with both preterm delivery and BV. BV-associated microorganisms, i.e., Mobiluncus, Prevotella, and Peptostreptococcus species, Porphyromonas asaccharolytica, Fusobacterium nucleatum, Mycoplasma hominis, and high numbers of Gardnerella vaginalis were significantly associated with preterm delivery; all species also strongly associated with BV (P = 0.0001 for each comparison). Mobiluncus curtisii and Fusobacterium nucleatum were recovered exclusively from women with preterm delivery. Our study clearly indicates that BV and its associated organisms are correlated with idiopathic premature delivery.

Permeation of human chorioamniotic membranes by Escherichia coli in vitro

OBJECTIVE

Our goal was to study the permeation of Escherichia coli through human chorioamniotic membranes in vitro.

STUDY DESIGN

Medium was placed in two compartments separated by chorioamniotic membranes obtained from six cesarean sections at term. The compartment faced by the chorion was inoculated with E. coli. Both compartments were sampled over 12 hours for observation of bacterial growth. Controls were performed without membranes.

RESULTS

In the compartment that was inoculated, concentration of E. coli increased from 10(6) to 10(10) colony-forming units per milliliter. In the compartment faced by amnion, bacterial growth was observed after 6 hours and reached 10(3) colony-forming units per milliliter. Permeation of E. coli was confirmed histopathologically. The change of glucose and lactate was linear. In the controls the concentration of E. coli increased to 10(7) (p < 0.001).

CONCLUSIONS

E. coli organisms permeate viable chorioamniotic membranes. The membranes constitute a weak barrier against ascending infection and do not inhibit bacterial growth.

A review of premature birth and subclinical infection

Premature birth causes high rates of neonatal morbidity and mortality. There are multiple causes of preterm birth. This article reviews the evidence linking subclinical infection and premature birth. Although maternal genital tract colonization with specific organisms has been inconsistently associated with preterm birth and/or premature rupture of membranes, some infections have been consistently associated with preterm delivery. The association of histologic chorioamnionitis with prematurity is a consistent finding, but the mechanisms require further study. The relationship between histologic chorioamnionitis infection and the chorioamnionitis of prematurity requires additional research. A varying number of patients in "idiopathic" preterm labor have positive amniotic fluid cultures (0% to 30%), but it is not clear whether infection preceded labor or occurred as a result of labor. Evidence of subclinical infection as a cause of preterm labor is raised by finding elevated maternal serum C-reactive protein and abnormal amniotic fluid organic acid levels in some patients in preterm labor. Biochemical mechanisms for preterm labor in the setting of infection are suggested by both in vitro and in vivo studies of prostaglandins and their metabolites, endotoxin and cytokines. Some, but by no means all, antibiotic trials conducted to date have reported decreases in prematurity. These results support the hypothesis that premature birth results in part from infection caused by genital tract bacteria. In the next few years, research efforts must be prioritized to determine the role of infection and the appropriate prevention of this cause of prematurity.

Characteristics of three vaginal flora patterns assessed by gram stain among pregnant women. Vaginal Infections and Prematurity Study Group

This study was undertaken to define the characteristics and persistence of vaginal flora in 7918 pregnant women at 23 to 26 weeks' gestation. Vaginal smears were categorized as normal (predominant lactobacilli), intermediate (reduced lactobacilli), or positive for bacterial vaginosis. The women with normal flora were least likely to have elevated vaginal pH, amine odor, milky discharge, or colonization by Gardnerella, Bacteroides, or genital mycoplasmas. Women with intermediate vaginal flora had intermediate frequencies of these clinical signs and microorganisms. Group B streptococci and yeast were associated with normal or intermediate flora, whereas Neisseria gonorrhoeae and Chlamydia trachomatis were recovered more frequently from women with intermediate flora or bacterial vaginosis. Trichomonas vaginalis was most associated with intermediate flora. At follow-up, 81% of the women with normal flora had remained normal. Of the women with intermediate flora, 32% acquired bacterial vaginosis and 30% shifted to normal flora. Only 12% of the women with bacterial vaginosis had shifted to normal flora. We conclude that there are two primary stable vaginal flora patterns (normal flora or bacterial vaginosis) and a third less distinct transitional flora pattern between these two.

The perinatal autopsy: a contemporary approach

As autopsy rates in general hospitals decline, interest in the perinatal autopsy continues to rise, reflecting the emergence of a vigorous specialty growing in parallel with fetal medicine, prenatal diagnosis and clinical genetics. Perinatal autopsies are best carried out in tertiary centres which provide these services. Meticulous documentation, flexibility of technique, intelligent use of laboratory tests and wide systematic histopathologic sampling are emphasized. Microbiologic examination is of particular value when carried out by a laboratory having a special interest in genital tract and perinatal pathogens. Karyotyping must be selective if resources are to be conserved and is most productive when there are multiple malformations. Perinatal autopsy is not complete without examination of the placenta and significant lesions should be clearly distinguished from curiosities and from changes secondary to fetal death. The pathologist's wider contribution to perinatal medicine includes providing high quality data to epidemiology units and auditing committees, contributing to the multidisciplinary management of prenatally diagnosed fetal abnormalities, monitoring iatrogenic disease patterns and supporting the process of perinatal grief management. Special problems and diagnostic challenges are to be found when investigating sudden, unexplained intrauterine fetal death, hydrops, bone dysplasias and complicated multiple pregnancies.